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Zeitschrift/Journal: Austrian Journal of Earth Sciences
Jahr/Year: 1999
Band/Volume: 92
Autor(en)/Author(s): Sachsenhofer Reinhard F.
Artikel/Article: Geodynamic Controls on Deposition and Maturation of Coal in the Eastern Alps. 185-194 © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at
Vl\ Osvr. (Scol. G-:>s. ISSN 02bl 7493 92 ••"'•!99: Ito-HM Whr. J., i 2000
Geodynamic Controls on Deposition and Maturation of Coal in the Eastern Alps
REINHARD F SACHSENHOFER1
6 Figures
Abstract Geodynamic processes control basin evolution and, therewith, coal-geological relevant parameters like number and geometry of seams and coal quality in terms of ash yield, sulphur content and maturity. Only minor amounts of coal accumulated within the Eastern Alps during the Variscan orogeny in Carboniferous time and at the southern passive continental margin of Europe during Triassic and Liassic time. Jet formed after the Cretaceous orogeny in strike-slip controlled settings. Major coal deposits in the Eastern Alps are related to basins, which formed during and after Tertiary continent-continent collision. A high number of thin seams was deposited in brackish environments in the Alpine foreland basin (Upper Bavarian coal district). The distribution of the seams is controlled by regressive/transgressive cycles. Non-marine coal in the Hausruck district formed during a late stage of the basin evolution. Several intramontaneous pull-apart basins originated after the main collisional event. They often contain a single thick coal seam. In these basins, coal facies variations are primarily controlled by high subsidence rates, whereas coal facies variations in the Köflach area (Styrian basin) are controlled by local processes, like the lateral migration of channels. The rank of pre-Tertiary coals ranges from sub-bituminous to semi-graphite and is a result of Mesozoic tectonothermal events. The rank of Tertiary coals is mainly controlled by Oligocene and Miocene heat flow. Extremely high heat flow was related to magmatic activity and the uplift of metamorphic core complexes. Tertiary coals in the vicinity to heat flow anomalies reach the bituminous stage in spite of shallow burial. In contrast, coal in the foreland basin, characterized by low heat flow, remained at low rank despite its deep burial.
Introduction second part, the relation between geodynamics, heat flow and coal rank is highlighted. Both accumulation and maturation of coal are intimately related to the geodynamic evolution of the lithosphere. The accumulation of thick peat deposits requires specific tec tonic conditions (e.g. subsidence rates, which are similar Coal-producing environments and the to peat accumulation rates; MCCABE, 1991; DIESSEL, 1992), geodynamic evolution of the Eastern Alps and coalification, which is mainly controlled by the factors of temperature and time, is a consequence of heat flow and Variscan evolution the depth of burial (e.g. TAYLOR et al., 1998). The first peat forming stages during the evolution of the The aim of this paper is to emphasize the relation be Eastern Alps are related to the final episodes of the Variscan tween geodynamics and coal formation using the example orogeny (KRAINER, 1993; Fig. 2). Westphalian A-C coals of the Eastern Alps. Monographs of coal in the study area accumulated in synorogenic settings ("foredeep") at the top are provided by WEBER & WEISS (1983), SACHSENHOFER of shallow marine sequences. Up to 9 seams interfinger (1987) and SCHULZ & FUCHS (1991). Therefore, the present with distributary bay and channel-fill deposits (RATSCHBA- paper focuses on typical and/or economically important CHER, 1987). Cretaceous low-grade metamorphism changed deposits. A simplified map of the Eastern Alps showing the the organic matter to semi-graphite, which has been mined distribution of main coal districts is presented in Fig. 1. Their west of Leoben (Fig. 1). E-W directed intramontaneous stratigraphic age and the time of coalification are indicated basins formed after the Variscan orogeny and were filled in Fig. 2, together with some information on the geodynamic with fluvial (Westphalian D to) Stephanian sediments. Thin evolution of the study area. coal seams in the Turrach and Steinach areas (east and Favourable conditions for the formation of coal occurred west of the Tauern window) accumulated in flood plains during different stages of the evolution of the Eastern Alps. and oxbow lakes on top of fining upward sequences This relation is dicussed in the first part of the paper. In the (KRAINER, 1993). Minor Stephanian coal also occurs south of
Address of the author 1 Institut für Geowissenschaften, Montanuniversität A-8700 Leoben Austria. E-mail: [email protected] © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at
186 R. F SACHSENHOFER
Austroalpine unit DID Penninic and Helvetic units ES3 Oligocene plutons Major faults lliil Neogene coal §1 Paleogene coal Cretaceous Coal (Turonian l Jet) © uretaceous coal (Campanian) © Jurassic "Gresten" coal Triassic "Lunz" coal © Carboniferous coal
Fig. 1 Sketch map of the Eastern Alps and position of selected coal basins. the Periadriatic Lineament in the Nassfeld area (Carnic ness of the coal was in the order of a few tenths of centime Alps). ters. However, due to the Alpine orogeny, the coal forms up to 9 m thick lenses arranged along the crests of E-W trend ing anticlines in the Lilienfeld area. Alpine evolution Jurassic "Gresten" coals are related to a major phase of Rifting/drifting transgression caused by the opening of the Penninic ocean. The post-Variscan evolution started with Permian rifting Liassic sediments were deposited near the southern margin and the opening of two oceans separating the Eastern of stable Europe. They host coal seams, which formed and the Southern Alps during the Middle Triassic (Hallstatt/ either subaquatically, resulting in sapropelitic coal interfin- Meliata ocean) and the Eastern Alps and stable Eu gering with marine limestones, or in relatively dry swamps rope during Early/Middle Jurassic times (Penninic ocean). within floodplain environments (SACHSENHOFER, 1987). Up Only minor coal deposits formed during this time interval to 16 seams with a maximum thickness of 1 m occur within (Fig. 2). the later facies realm. Tertiary tectonics transported the During the Late Triassic time the Northern Calcareous coal-bearing sequence to its present-day position near the Alps formed the northern passive continental margin of the northern margin of the Alps (Fig. 1). Gresten coals with a Hallstatt/Meliata ocean. Thick, mainly shallow-water, car bonates were deposited. A major sea level fall and tectonic Fig. 2 events in Carnian time resulted in southward propagation of Overview showing the time of coal deposition, time of coalification, clastic sediments over the Austroalpine shelf region and the and coalification temperatures within the Eastern Alpine realm. The deposition of brackish "Lunz" coals (SACHSENHOFER, 1987). plot is mainly based on data published by SACHSENHOFER & RAN- Today, these coals occur in different nappes within the TITSCH (1997). Note, that only magmatic events with a Tertiary age northeastern Calcareous Alps (Fig. 1). The original thick are indicated. © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at
Carbonifer. Permian Triassic Jurassic Cretaceous Eocene Oligocene Miocene Plioc Early I Late Early I Mia, I L. Early I Late Early I Late Early I Middle | Late l i I -i—i—i—i—i—i i I i I n 1—Break-in—• 1 300 200 100 40 time-scale 30 20 10
Variscan Cretaceous orogeny Tertiary orogeny orogeny Syn-collisional stage Post-collisional stage
35-130 . # Northern Alpine foreland Upper Bavarian Hausruck Uli • strict Tnmmelkam T # 70-90 European passive margin Sresten coal 75-150 •
Penninic Ocean mi\ in 111111 ifill 1 Austroalpine plate (esp. Northern Calc. Alps) 360-410 * ?-% 25-1. Forelam8d illnz coal 5u coal 1 /Inntal basin -#? <- Noric depression <50 60-150 40-9 —• SMeisiipy 240-300 Lavant Pasin 0@U@@ge|b, Styrian Pasin
HallstattiMeliata Ocean Jg Southalpine plate (Nassteld area) Retroarc foreland Velenje -#?<- m- -m 270 uptol80 uptoloO Lignite Bituminous coal Meta-anthr./semi-graphite 25-11Q+- Temperature (°C) S Time of coal Sub-bitum. coal Anthracite/Meta-anthr. Tertiary magmatic events deposition Time of codification © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at 188 R. F. SACHSENHOFER Doggerian age occur also in the autochthonous foreland ic activity along the Periadriatic Lineament (VON BLANKEN- beneath Tertiary sediments. BURG & DAVIES, 1995), nappe stacking, and the formation of the Northern Alpine foreland basin (Molasse basin). Coal deposition occurred during different stages of the evolution Cretaceous orogeny of the foreland basin: Subduction of the Hallstatt/Meliata ocean and the Late • An up to 3 m thick Eocene coal seam formed during an Jurassic to Middle Cretaceous collision between the South early transgressive stage of its evolution and overlies a and East Alpine blocks resulted in Cretaceous nappe stack subsiding floodplain. ing within the Austroalpine realm. Thereafter, subduction of • Ongoing Oligocene collision resulted in increased sub the Penninic ocean beneath the active margin of the Aus sidence of the foreland and a high relief in the Western troalpine microplate began. Oblique subduction controlled Alps. Alpine detritus was delivered by alluvial fans into the the formation of Late Cretaceous Gosau basins on top of basin and was transported by an axial drainage system in the Calcareous Alps (FAUPL & WAGREICH, 1996). No coal an eastward direction into the more than 1000 m deep formed during the collisional event, but some deposits oc sea. Late Oligocene coal intercalating with bituminous cur within the Gosau basins. limestones accumulated near the shoreline in brackish The coal-bearing Lower Gosau Group (Turanian to Cam- environments. Mining activity was restricted to the alloch- panian) comprises terrestrial to shallow marine deposits, thonous foreland (Upper Bavarian coal district). The total which were laid down during a phase of major strike-slip number of coal seams varies laterally between 20 and 60, faulting. Drift wood transformed into jet forms distinct layers but average seam thickness is only 0.3-0.5 m. The spatial within shallow marine Turanian sediments (KOLLMANN & distribution of the seams is controlled by regressive/ SACHSENHOFER, 1998). Locally these layers, which were transgressive cycles (GEISSLER, 1975; STEININGER et al., mined extensively during the 15th and 16th century (FREH, 1988/89; Fig. 3). The high number of seams, the control 1956), occur close to "usual" coal. Up to 8 coal seams also by regressive/transgressive cycles and intense tectonic occur within deltaic sediments of Campanian age in the deformation are common features of coal in foredeep Grünbach area (SACHSENHOFER, 1987). settings (e.g. DIESSEL, 1992). • The foreland basin was filled during the Early Miocene time. Middle to Late Miocene freshwater lignite was de Tertiary orogeny: Syn-collisional stage posited in the Trimmelkam/Hausruck area during a late Following Late Cretaceous to Eocene subduction of the stage of basin evolution. The coal-bearing sequence Penninic ocean, the Austroalpine block collided with stable overlies marine sediments with an erosional unconformity. Europe. The collision resulted in slab breakoff and magmat- Thickness and distribution of three up to 4 m thick coal W 300000000000oooooooooooo0 o c 03 1— CD ooooooooooooooooOOOOOOOOOO.. o O) >ooooooooooooooooooooo UJ OOOOOOOOOOOOOOOOOOOO CA ,7». ooocoooooooooooooo >ooooooooooooooooo< ooocoooooooooooooo >oooooooooooooocoo OCOOOOOOOOOOOOCO Hausham >ooooooooooooooo öS COOOOCOOOOOOOC O^O ^^3 » ö ö o önö„<>A<>ÄQs Marienstein • Lech Isar Brackish sediments lo"l Freshwater sediments 2l—I (seam & seam number) I I Marine sandstone Fig. 3 Schematic W-E cross-section through the Upper Bavarian coal district (modified after GEISSLER, 1975). Position of cross-section is shown in Fig 1. Note, that positions of seams are shown only for the Hausham, Penzberg and Peiting areas. A high number of relatively thin seams is typical for foreland basins. The regional distribution of the deposits is controlled by regressions and transgressions. © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at ?eoc ;•' 189 seams are controlled by the underlying erosional relief (1993), the latter deposits formed in a retroarc-foreland (GROISS, 1989). basin. Oligocene coal also formed in the Inntal basin near Häring (Fig. 1), paleogeographically near the southern bor Tertiary orogeny: Post-collisional stage der of the foreland basin. Yet, because the basin is control led by Early Oligocene transtension (ORTNER & SACHSEN- Final compression across the Eastern Alps in Miocene HOFER, 1996) rather than by flexure, it is discussed separate time was accomodated by orogen-parallel eastward extru ly. Sedimentation started within an alluvial fan setting. The sion of the central Eastern Alps along northeast (e.g. alluvial fan is overlain by a sulphur-rich seam, which shows Salzach-Enns fault) and southeast trending strike-slip a marine influence. Average thickness of the 1 km2 wide zones (e.g. Periadriatic Lineament; RATSCHBACHER et al., seam is 4 m (max. 12 m). The coal grades upward into 1991). Intramontanous basins formed at oversteps of major sapropelitic rocks and marls, which accumulated in a 200 m strike-slip faults. Contemporaneously, E-W extension result deep sea (STINGL & KROIS, 1991; Fig. 4). ed in tectonic denudation and rapid uplift of metamorphic Paleogene coals also formed north (Zrece) and south of core complexes (Tauern and Rechnitz windows), formation the eastern section of the Periadriatic Lineament (e.g. of the Styrian basin and magmatic activity at the eastern Trbovlje, Makole in Slovenia; Fig. 1). According to TARI et al. margin of the Alps (TARI, 1994; EBNER & SACHSENHOFER, Häring Leoben Fohnsdorf Velenje (Wartinberg Shaft) (Well Gabelhofen) Oligocene Miocene Pliocene >„o_o„<: f_\LT \!/_SJ ''::••••-•;:•••:.- r^ > <^„<~>„^| _ f-u-'-o A, j , „ J, H >„o_o_ > O O > o o 3 Lacustrin e E e c c 10 0 m 10 0 m 10 0 m -lyin g mi r >h(?) - Lacustrir i ^^M Lo w 3rack k 0 Low-lying •• mire T— Low-lying > ' • '• ••• \ I 3 : J ~ w " \y" s-j LL —r • . ... . • • • • >„0„0_ Fluviatil e Brackish-Lacustrin > o 6 Shale, silt , marl Sandstone Coal Bitumino JS shale, marl > o o < Conglomerate Fig. 4 Stratigraphic columns of coal-bearing pull-apart basins of Tertiary age and reconstruction of moor-types (STINGL & KROIS, 1991; SACHSENHOFER et al., a in press; LACKENSCHWEIGER, 1937; GRUBER & SACHSENHOFER, 1999; MARKIC & SACHSENHOFER, 1997). In difference to foreland basins, only one, but thick seam is present. The sedimentary succession, controlled by high subsidence rates, indicates the drowning of the peat. © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at ;9-; R. F SACHSENHOFER 1995). Major coal deposits formed in strike-slip basins and bearing troughs ranges from 0.5 to 3 km. Coal facies varia in the Styrian basin. tions are primarily due to local autosedimentational proc Typically, Miocene basins along major strike-slip faults are esses (e.g. migration of active channels), and not due to filled from bottom to top by fluvial sediments, a single thick basin-wide events (KOLCON & SACHSENHOFER, 1999) indi coal seam, a sapropelite, and lacustrine/brackish sedi cating relatively low subsidence rates. More continuous ments (e.g. Leoben and Fohnsdorf basins in the Noric de seams formed at the same time in the Eibiswald area. pression; Fig. 4). This sequence reflects the drowning of the Two lacustrine seams with a thickness ranging from 0.5 to peat due to high subsidence rates characteristic for pull- 2 m have been mined. The upper seam, overlain by apart basins. Depending on the depositional environment, coastal plain deposits, reaches a lateral extension of ca. the coal properties differ significantly. Coal in the Leoben 25 km2. Late Miocene lignite formed during final stages basin accumulated in a raised bog and is poor in ash and of the basin evolution in the central part of the Styrian sulphur. Coal in the Fohnsdorf basin formed in a swamp basin. These fluvio-lacustrine coals reached only local influenced by a brackish lake and is rich in ash and sul significance. phur. Movements along the Periadriatic Lineament continued during the Pliocene (FODOR et al., 1999). They resulted in the formation of the deep Velenje pull-apart basin hosting a Rank - a mirror of orogenic heat flow more than 100 m thick lignite seam (Fig. 4). Because of high Permian to Tertiary tectonothermal events are responsible subsidence rates and similarity to basins along the Noric for the different rank of coals in the Eastern Alps, which depression it was filled with fluvial sediments, a drowning ranges from lignite to semi-graphite. coal seam and lacustrine deposits (MARKIC & SACHSENHO FER, 1997). Pre-Oligocene tectonothermal events Formation of the Lavant basin is related to Late Miocene movements along dextral strike-slip faults. From a coal- Cretaceous temperatures in the Veitsch nappe were as geological point of view, it differs significantly from other high as 360-410 °C (RAITH & VALI, 1998) and resulted in the strike-slip basins. The main differences are a higher number formation of semi-graphite. Due to significantly lower tem (up to 5) of laterally more continuous, but relatively thin peratures (<300 °C), coals in the Turrach and Steinach (generally 1-2 m), seams. Probably the differences reflect areas reach only the meta-anthracite stage (SACHSEN differing subsidence rates. HOFER & RANTITSCH, 1997). Similar Cretaceous tempera Contemporaneously, with strike-slip faulting along the tures occurred in the Nassfeld area, but RANTITSCH (1997) Noric depression, the Styrian basin formed on top of the speculates that coalification occurred already during the eastward moving crustal wedge (EBNER & SACHSENHOFER, Early Permian time as a result of strongly elevated heat 1995). Several shallow (half)grabens formed in the Köflach flow. area during the onset of basin formation and were filled with The rank of Triassic "Lunz" coals in the northeastern part Early Miocene coal-bearing fluvial sediments (HAAS et al., of the Northern Calcareous Alps ranges from sub-bitumi 1998). The lateral continuity of the seams is low. They pinch nous to medium volatile bituminous coal (0.43-1.20% vit- out above basement highs, but reach a thickness up to rinite reflectance, Rr; Fig. 5). Coalification temperatures are 60 m within the depocenters. The diameter of the coal- in the range of 60-150 °C (Fig. 2). Isoreflectivity lines are Vitrinite Reflectance • Jurassic "Gresten" coal Northern front of the (%Rr) ° Triassic "Lunz" coal Northern Calcareous Alps 1.0-1.2 I 10.6-0.8 0.8-1.0 •0.4-0.6 Gresten r : i .:4cr'. -.i---:> --'0..',;;:;:; 10 20 km Periad<, "c Lin Fig. 5 Map showing vitrinite reflectance of Triassic "Lunz" coals in the northeastern part of the Northern Calcareous Alps and of Jurassic "Gresten" coals in the accretionary wedge north of the Northern Calcareous Alps (SACHSENHOFER, 1987). © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at G':^Jv i;v-i:': Ccll'o;. Di IX;|.:r.::i ic;'i :ir;1 M.ü i: n r.i' :>\ C:;:\ \r lie- I-o^'.rr- A\\:.: 191 displaced along nappe boundaries, indicating pre-tectonic gin of the Alps. It is at least partly a result of magmatic coalification. An eastward increase in rank can be observed activity (SACHSENHOFER, 1994). However, maximum heat in all tectonic units. It is still unclear, whether this is a conse flow occurs south of the center of magmatic activity. There quence of an eastward increase in tectonic burial during the are two alternative interpretations. Both, a shallow pluton Early Cretaceous time (closure of the Hallstatt/Meliata that is unknown up to now, beneath the heat flow maximum ocean) or a result of laterally varying Jurassic/Early Creta and another metamorphic core complex could explain the ceous heat flow. observed anomaly (SACHSENHOFER et al., 1998). In con Late Cretaceous "Gosau" coal reaches the sub-bitumi trast to the above areas, the northern margin of the Alps nous stage. Probably coalification ended before the Eocene remained cold. Slightly elevated heat flow along the deformation of the Gosau basins. Coalification tempera northern rim of the foreland basin is probably an effect of tures were in the order of 40-90 °C, according to vitrinite northward migration of temperated fluids from beneath reflectance studies. the Alps. Early/Middle Miocene heat flow controls coalification of Oligocenei'Miocene heat flow Early Miocene coals in intramontaneous basins and in the Styrian basin: Coalification of Tertiary coals is controlled by Oligocene • Bituminous coal (0.65%Rr) occurs in the western Enns and Miocene heat flow patterns. During the last decade, valley (Wagrain) and in the. western Noric depression heat flow histories of many basins were reconstructed ap (Tamsweg), whereas lignite occurs in more eastern ba plying numeric modelling techniques (YALCIN et al., 1997). sins. Westward increase in rank is a consequence of the SACHSENHOFER (in prep.) used this information together with heat flow maximum above the uplifting Tauern window. vitrinite reflectance patterns of surface samples to design Whereas rank decreases continually with the distance heat flow maps for Oligocene, Early/Middle Miocene and from the Tauern window in the Enns valley, coalification Late Miocene times (Fig. 6). Here, the maps are discussed patterns are more complicated along the Noric depres with respect to the geodynamic evolution of the Alps and sion. This is due to a local heat flow high in the Leoben the resulting maturation patterns. area and an exceptionally thick basin fill in the Fohnsdorf basin (SACHSENHOFER, 1992; SACHSENHOFER et al. a, in Oligocene press). Both effects resulted in a similar rank (sub-bitumi nous coal, 0.40-0.55%Rr). Oligocene heat flow patterns (Fig. 6A) exhibit a distinct asymmetry. Very low heat flow along the northern margin of • Early Miocene Eibiswald coals in the southwestern Styri the Eastern Alps, a thermal effect of nappe stacking and an basin are located at the margin of a huge heat flow high sedimentation rates, contrasts with extremely elevated anomaly. Therefore, these are sub-bituminous coals (0.4- heat flow along their southern margin. The latter is a conse 0.55%Rr), whereas Early Miocene Köflach coals in the quence of Oligocene magmatic activity. northeastern part of the basin are only lignites The observed heat flow variations help to understand (0.30%Rr). Coal in the Makole area is located within the coalification patterns of Paleogene coals at the northern heat flow anomaly and even reached the medium vola and southern edge of the Eastern Alps. tile bituminous stage (1.4%Rr; SACHSENHOFER et al., b, in press). • Due to slightly elevated heat flow in the Inntal basin and • The rank of Oligocene coals along the southern and east extremely low heat flow in the allochthonous foreland ern margins of the Bohemian massif is locally raised (up basin, sub-bituminous coals (ca. 0.5%Rr) occur in Häring to 0.55%Rr). Perhaps this is due to the described north and in the Upper Bavarian coal district, although the latter ward migration of temperated fluids and slightly elevated was buried significantly deeper (>3 km; JACOB et al., heat flow along the northern rim of the foreland basin. 1982) than the Häring coal (<2 km; ORTNER & SACHSEN HOFER, 1996). The rank of Jurassic "Gresten" coals ranges from sub- • Maximum burial of the Eocene Zrece coal at the southern bituminous (0.55%Rr) to high volatile bituminous coal slope of the Pohorje Mountain was significantly below (1.0%Rr; Fig. 4). These coals probably matured during 1 km (HAMRLA, 1988). However, because of extremely ele deep (3-5 km?) early Miocene burial. vated heat flow due to the emplacement of the Pohorje tonalite, the coal reaches the bituminous stage (0.8%Rr). Late Miocene Oligocene coal with an even higher rank (1.0%Rr) occurs close to an Oligocene volcanic center south of the Peri- Heat flow decreased during the Middle and Late Miocene adriatic Lineament. The rank of Oligocene coals decreas time in the central and southeastern part of the Eastern Alps (Fig. 6C). In the Styrian Basin heat flow was elevated above es with the distance from the Periadriatic Lineament. Coal 2 2 in the Trbovlje area is only a lignite (ca. 0.3%Rr). basement highs (up to 100 mW/m ), and 60 to 70 mW/m in troughs with thick Neogene sediments. The relatively high heat flow is a result of thinned crust beneath the Pannonian Early/Middle Miocene basin. Tectonic turmoil during the Early/Middle Miocene time Because of relatively low heat flows and shallow burial, all had a significant influence on heat flow patterns (Fig. 6B). post-Early Miocene coal deposits contain lignite. The heat Extremely elevated heat flow occurred in the vicinity of flow in the foreland basin has been low since Oligocene metamorphic core complexes (Tauern and Rechnitz win times. Consequently, the rank of deeply buried Eocene coal dows). They result from rapid uplift of hot basement rocks at the base of its Tertiary fill is low and a vitrinite reflectance (e.g. DUNKL et al., 1998). Extremely elevated heat flow of 0.6%Rr is reached only below thrust sheets at ca. 4 km 2 (>200 mW/m ) also occurred along the southeastern mar depth. © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at 192 R. F SACHSENHOFEH C) LATE MIOCENE (~ 6 m.a.) jiillllllii Penninic windows i.: Sites of heat flow estimates B) EARLY/MIDDLE MIOCENE^ (17-15 m.a.) •'" • ~ Rechnitz w. Oligocene & Early/Middle Miocene K^ volcanic centers A) LATE OLIGOCENE (25 - 30 m.a.) 100 km 2 • <55mW/m 55 - 70 mW/m2 75- 150mW/m2 > 150 mW/m2 © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at I IÜ3 Acknowledgements HAMRLA, M., 1988: Contribution to the geology of coal deposits in the Zrece area and reflectance-based ranking of ist coal. - The paper benefited from discussion with many colleagues and Geologija, 30, 343-390. from careful reviews by F. NEUBAUER (Salzburg) and M. WAGREICH (Vienna). Special thanks are to I. DUNKL (Tübingen), J. FRANCU HASENHÜTTL C, KRALJIC M., SACHSENHOFER R. F, JELEN B. & RIEGER (Brno), W. GRUBER, C. HASENHÜTTL and G. RANTITSCH (Leoben). R., 2000: Source rocks and hydrocarbon generation in Slovenia Parts of this work were funded by the Austrian National Science (Mura Depression, Pannonian Basin). - Marine and Petroleum Foundation (FWF grants P10738-Tec, P14025-Tec). Geology, in press. HILTMANN, W., KUCKELKORN, K. & WEHNER, H., 1995: Thermische Entwicklung und KW-Bildungspotential der in der Bohrung Hin- References delang 1 (Allgäuer Alpen) durchteuften tektonischen Einheiten. - Geologica Bavarica, 100, 175-197. DIESSEL, C. F K., 1992: Coal-bearing Depositional Systems, 721 p., JACOB, H., KUCKELKORN, K. & MÜLLER, M., 1982: Inkohlung und Berlin (Springer-Verlag). Tektonik im Bereich der gefalteten Molasse. - Erdöl und Kohle, DOLL, C, SACHSENHOFER, R. F & KULKE, H., 1997: Numerical mod 35, 510-518. elling of heat flow history in the Styrian Basin (Austria) - A comparison between predicted and measured data from well KOLLMANN, H. A. & SACHSENHOFER, R. F, 1998: Zur Genese des Gagats von Garns bei Hieflau (Oberkreide, Steiermark). - Mitt. Petersdorf 1. - Terra Nostra, 97, 28. Ref. Geol. Paläont. Landesmuseum Joanneum, SH2: 223-238. DUNKL, I., GRASEMANN, B. & FRISCH, W., 1998: Thermal effect on KOLCON, I. & SACHSENHOFER, R. F., 1999: Petrography, palynology upper plate during core-complex denudation: a case study from and depositional environments of the early Miocene Oberdorf the Rechnitz Window, Eastern Alps. - Tectonophysics, 297, 31- 50. lignite seam (Styrian Basin, Austria). - Int. J. Coal Geol., 41, 275- 308. EBNER, F. & SACHSENHOFER, R. F., 1995: Paleogeography, subsid KRAINER, K., 1993: Late- and Post- Variscan sediments of the East ence and thermal history of the Neogene Styrian Basin (Pannon- ern and Southern Alps. - In: RAUMER, J. & NEUBAUER, F., (eds.): ian basin system, Austria). -Tectonophysics, 242, 133-150. Pre-Mesozoic Geology of the Alps, pp. 537-564, Berlin (Sprin EDER, N., NEUBAUER, F. & SACHSENHOFER, R. F, 1999: On the edge ger-Verlag). of the extruding wedge: Neogene kinematics and geomorpholo- gy along the southern Niedere Tauern, Eastern Alps. - Tübinger LACKENSCHWEIGER, H., 1937: Die Braunkohlenmulde von Leoben. - Geowiss. Arbeiten, Series A, 52, 47-48. Zs. Berg-, Hütten-Salinenwesen Dtsch. Reiche, 85, 209-213. FAUPL, R & WAGREICH, M., 1996: Basin analysis of the Gosau Group LADWEIN, W., SCHMIDT, F, SEIFERT, P & WESSELY, G., 1991: Geody- of the Northern Calcareous Alps (Turonian-Eocene, Eastern namics and generation of hydrocarbons in the region of the Alps). - In: WESSELY, G. & LIEBL, W. (eds.): Oil and Gas in Alpidic Vienna basin, Austria. - In: SPENCER, A. M., (ed.): Generation, Thrustbelts and Basins of Central and Eastern Europe, EAOG 5, accumulation, and production of Europe's hydrocarbons, Spec. pp. 127-135, London (Geological Society). Publ. of the EAPG, 1, pp. 289-305, Oxford (Oxford University Press). FERREIRO-MÄHLMANN, R., 1994: Zur Bestimmung der Diagenese höhe und beginnender Metamorphose - Temperaturgeschichte MARKIC, M. & SACHSENHOFER, R. F, 1997: Petrographic compositon und Tektogenese des Austroalpins und Südpenninikums in Vor and depositional environments of the Pliocene Velenje lignite arlberg und Mittelbünden. - Frankfurter geowiss. Arb., 14, 1-498. seam (Slovenia). - Int. J. Coal Geology, 33, 229-254. FODOR, L., JELEN, B., MÄRTON, E., SKABERNE, D., CAR, J. & VRABEC, MCCABE, P J., 1991: Tectonic controls on coal accumulation. - Bull. M., 1999: Miocene-Pliocene tectonic evolution of the Slovenian Soc. Geol. France, 162, 277-282. Periadriatic fault: Implications for Alpine-Carpathian extrusion ORTNER, H. & SACHSENHOFER, R. F, 1996: Evolution of the Lower models. -Tectonics, 17, 690-709. Inntal Tertiary and constraints on the development of the source FRANCU, J., MÜLLER, R, SUCHA, V & ZATKALIKOVA, V, 1990: Organic area.- In: WESSELY, G. & LIEBL, W. (eds.): Oil and Gas in Alpidic matter and clay minerals as indicators of thermal history in the Thrustbelts and Basins of Central and Eastern Europe, EAOG 5, Transcarpathian depression (east Slovakian Neogene basin) pp. 237-247, London (Geological Society). and the Vienna basin. - Geologica Carpathica, 41, 535-546. RAITH, J. G. & VAU, H., 1998: Fibrous chlorite and muscovite from FREH, W., 1956: Alte Gagatbergbaue in den nordöstlichen Ost the Kaisersberg graphite mine, Styria, Austria. - Canadian Min alpen. - Min. Mitt. Joanneum, 1956, 1-14. eralogist, 36, 741-754. FÜGENSCHUH, B., 1995: Thermal and kinematic history of the Bren RANTITSCH, G., 1997: Thermal history of the Carnic Alps (Southern ner area (Eastern Alps, Tyrol). - PhD thesis, ETH Zürich, 226 pp. Alps, Austria) and its paleogeographic implications. - Tectono physics, 272, 213-232. GEISSLER, P, 1975: Räumliche Veränderung und Zusammenset zung der Flöze in den Kohlenbergwerken Hausham und Penz- RATSCHBACHER, L., 1987: Stratigraphy, tectonics, and paleogeogra berg. - Geologica Bavarica, 73, 61-106. phy of the Veitsch nappe (Greywacke zone, Eastern Alps, Aus tria): a rearrangement. - In: FLÜGEL, H. W., SASSI, F. P, GRECULA, GROISS, R., 1989: Geologie und Kohlebergbau im Hausruck P, eds., Pre-Variscan and Variscan events in the Alpine-Mediter (Oberösterreichische Molasse). - Arch. Lagerst.forsch. Geol. ranean belts, Mineralia Slovaca- Monograph, pp. 407-414, Bra Bundesanst., 11, 167-178. tislava (Alfa). GRUBER, W. & SACHSENHOFER, R. F, 1999: Beckenbildung und Kohlefazies: Erste Ergebnisse aus dem Fohnsdorfer und RATSCHBACHER, L., FRISCH, W., LINZER, H.-G., & MERLE, 0., 1991: Lateral extrusion in the Eastern Alps, 2: Structural analysis. - Seegrabener Tertiär. - Kurzfassungen 4. Österr. Sediment Work shop: 9-10. Tectonics, 10, 257-271. SACHSENHOFER, R. F, 1987: Fazies und Inkohlung mesozoischer HAAS M., DAXNER-HÖCK G., DECKER K., KOLCON I., KOVAR-EDER J., Kohlen der Alpen Ostösterreichs. - Mitt. österr. geol. Ges., 80, MELLER B. & SACHSENHOFER, R. F., 1998: Palaeoenvironmental studies in the Early Miocene lignite opencast mine Oberdorf, 1-45. (N Voitsberg, Styria, Austria). - In: STEININGER, F. F., (ed.): The SACHSENHOFER, R. F., 1992: Coalification and thermal histories of Early Miocene Lignite Deposit of Oberdorf N Voitsberg (Styria, Tertiary basins in relation to late Alpidic evolution of the Eastern Austria), Jb. Geol. Bundesanst., 140, 483-490. Alps. - Geol. Rundschau, 81, 291-308. © Österreichische Geologische Gesellschaft/Austria; download unter www.geol-ges.at/ und www.biologiezentrum.at 194 SACHSENHOFER, R. F, 1994: Petroleum generation and migration in STEININGER, F. F., RÖGL, F., HOCHULI, R & MÜLLER, C, 1988/89: the Styrian Basin (Pannonian Basin system, Austria): An integrat Lignite deposition and marine cycles. The Austrian Tertiary lignite ed geochemical and numeric modelling study. - Marine and deposits - A case history. - Sitzber. Österr. Akad. Wiss., math.- Petroleum Geology, 11, 684-701. naturwiss. Kl., Abt. I, 197, 309-332. SACHSENHOFER, R. F: Syn- and post-collisional heat flow in the STINGL, V. & KROIS, R, 1991: Marine Fan Delta Development in a Tertiary Eastern Alps. - Int. J. Earth Sciences, in prep. Paleogene Interior Alpine Basin (Tyrol, Austria). - Neues Jb. SACHSENHOFER, R. F. & RANTITSCH, G., 1997: Das Inkohlungsbild Geol. Paläont. Monatshefte, 1991, 427-442. österreichischer Kohlenlagerstätten und Temperaturgeschichten TARI, G., 1994: Alpine tectonics of the Pannonian Basin. Unpubl. alpiner und außeralpiner Sedimentbecken. - In: WEBER, L, ed., PhD thesis, Rice University, Houston, Texas, 501pp. Handbuch zu den Lagerstätten der Erze, Industrieminerale und TARI, G., BÄLDI, T & BÄLDI-BEKE, M., 1993: Paleogene retroarc Energierohstoffe in Österreich, Archiv Lagerst.forsch. Geol. Bun- flexural basin beneath the Neogene Pannonian basin: a geody- desanst., 19, 503-514. namic model. -Tectonophysics, 226, 433-455. SACHSENHOFER, R. F., DUNKL, I., HASENHÜTTL, C. &JELEN, B., 1998: TAYLOR, G. H., TEICHMÜLLER, M., DAVIS, A., DIESSEL, C. F. K., LITTKE, Miocene thermal history of the southwestern margin of the Styri R, & ROBERT, R, 1998: Organic Petrology, 704 p., Berlin-Stuttgart an Basin: vitrinite reflectance and fission track data from the (Borntraeger). Pohorje/Kozjak area (Slovenia). - Tectonophysics, 297, 17-29. VON BLANCKENBURG, F. & DAVIES, J. H., 1995: Slab breakoff: A SACHSENHOFER, R. F, KOGLER, A., POLESNY, F, STRAUSS, P & WAG- model for syncollisional magmatism and tectonics in the Alps, REICH, M., 2000 (a): The Neogene Fohnsdorf Basin: Basin forma Tectonics, 14, 120-131. tion and basin inversion during lateral extrusion in the Eastern Alps/Austria). - Int. J. Earth Sciences, in press. WAGNER, L., KUCKELKORN, K. & HILTMANN, W., 1986: Neue Ergeb nisse zur alpinen Gebirgsbildung Oberösterreichs aus der Boh SACHSENHOFER, R. F., JELEN, B., HASENHÜTTL, C, DUNKL, I. & RAIN rung Oberhofen 1 - Stratigraphie, Fazies, Maturität und Tektonik. ER, T, 2000 (b): Thermal history of Tertiary basins in Slovenia - Erdöl, Erdgas, Kohle, 102, 12-19. (Alpine-Dinaride-Pannonian junction). - In: TARI, G., ed., Extreme Miocene Extension in the Eastern Alps/Pannonian Basin Transi WEBER, L. & WEISS, A., 1983: Bergbaugeschichte und Geologie der Österreichischen Braunkohlenvorkommen. - Arch. Lagerst, tional Zone, Geol. Society Amer. Spec. Pap., in press. forsch. Geol. Bundesanst., 4, 1-317. SCHMIDT, F. & ERDOGAN, L. T, 1993: Basin modelling in an over- thrust area of Austria. - In: DORE, A. G., AUGUSTSON, J. H., YALCIN, M. N., LITTKE, R. & SACHSENHOFER, R. F., 1997: Thermal history of sedimentary basins. - In: WELTE, D. H. et al., (eds.): HERMANRUD, C, STEWART, D. J., SYLTA, Ö., eds., Basin Modelling: Petroleum and Basin Evolution, pp. 73-167, Berlin (Springer- Advances and Applications, Norwegian Petr. Soc. (NPF) Spec. Verlag). Publ., 3, pp. 573-581, Amsterdam (Elsevier). SCHMIDT, F. & ERDOGAN, L. T, 1996: Paleohydrodynamics in explo ration. - In: WESSELY, G. & LIEBL, W., eds., Oil and Gas in Alpidic Thrustbelts and Basins of Central and Eastern Europe, EAOG 5, pp. 255-265, London (Geological Society). SCHULZ, O. & FUCHS, H. W., 1991: Kohle in Tirol: Eine historische, Manuscript received: 26. 01. 2000» kohlenpetrologische und lagerstättenkundliche Betrachtung. - Revised version received: 26. 02. 2000 • Arch. Lagerst.forsch. Geol. Bundesanst., 13, 123-213. Manuscript accepted: 17. 03. 2000»